An Evaluation Of The Suitability Of Some Basement Rocks From Oban Massif, Southeastern Nigeria, For Engineering Construction Purposes

Abstract

The​ ​physical​ ​and​ ​engineering properties​ ​of​ ​some​ ​basement​ ​rocks​ ​from​ ​parts​ ​of​ ​Oban​ ​Massif,​ ​Southeastern​ ​Nigeria​ ​were investigated​ ​to​ ​ascertain​ ​their​ ​suitability​ ​for​ ​civil​ ​engineering construction​ ​purposes.​ A total of 19​ ​representative rock ​samples comprising of granites and granodiorite​s, were​ ​obtained​ ​from​ ​three​ ​quarries​ ​in​ ​Akamkpa​ ​Local​ ​Government​ ​Area​ ​of​ ​Cross River​ ​State, southeastern part of Nigeria.​ ​The​ ​rock​ ​samples​ ​were​ ​crushed​ ​into​ ​aggregates​ ​and​ ​their​ ​physical​ ​and​ ​mechanical properties​ ​were​ ​assessed.​ ​The​ ​results​ ​obtained​ ​showed​ ​that​ ​the​ ​specific​ ​gravity​ ​ranged​ ​from 2.60-2.72,​ ​water​ ​absorption​ ​0.30-0.96%,​ ​aggregate​ ​impact​ ​value​ ​​12-30%, aggregate​ ​crushing​ ​value,​ ​12-33%,​ ​flakiness​ ​and​ ​elongation​ ​Indices​ ​both ranged​ ​from​ ​14-29%,​ ​the uniaxial​ ​compressive​ ​strength​ ​fell​ ​between​ ​190​ ​and​ ​209NM/m​,^{2​ ​​}and​ ​the​ ​Los​ ​Angeles​ ​abrasion gave​ ​14-41%.​ ​Petrographic​ ​studies​ ​suggested​ ​the​ ​rocks​ ​are​ ​granites​ ​and​ ​granodiorites.​ ​Results​ ​obtained from​ ​the​ ​research​ ​were​ ​compared​ ​with​ ​known​ ​engineering​ ​specifications.​ ​Such​ ​comparisons​ ​showed​ ​empirical​ ​relationships​ ​between​ ​the​ ​physical​ ​and​ ​the​ ​mechanical​ ​characteristics​ ​of​ ​the materials​ ​tested.​ ​These empirical relationships can, thus, be​ ​employed​ ​to​ ​save​ ​cost​ ​in​ ​future​ ​site​ ​investigations.​ ​Petrographic​ ​studies and​ ​engineering​ ​properties​ ​indicate​ ​that​ ​aggregates​ ​derived​ ​from​ ​the​ ​fresh​ ​basement​ ​rocks​ ​in​ ​the​ ​study areas​ ​are​ ​capable​ ​of​ ​withstanding​ ​heavy​ ​traffic,​ ​foundation​ ​loads​ ​and​ ​are​ ​generally​ ​suitable​ ​for​ ​most civil​ ​engineering construction​ ​purposes.​ ​It​ ​is​ ​also​ ​expected​ ​that​ ​the​ ​interpretation​ ​and​ ​ranking​ ​of​ ​the​ ​test​ ​results​ ​will provide​ ​a​ ​suitable​ ​guide​ ​to​ ​prospective​ ​clients​ ​of​ ​quarry​ ​operators​ ​as​ ​they​ ​can​ ​now​ ​have​ ​some​ ​scientific basis​ ​for​ ​selecting​ ​materials​ ​needed​ ​for​ ​different​ ​construction​ ​works.​ ​To​ ​achieve​ ​this, quarry​ ​operators must​ ​test​ ​and​ ​advertise/publicize​ ​the​ ​properties​ ​of​ ​their​ ​products​ ​for​ ​public​ ​consumption.